Jacob's Staff

The term Jacob's staff, also cross-staff, a ballastella, a fore-staff, or a balestilha, is used to refer to several things. This can lead to considerable confusion unless one clarifies the purpose for the object so named. The two most frequent uses are:

  • in astronomy and navigation for a simple device to measure angles, later replaced by the more precise sextants;
  • in surveying for a vertical rod that penetrates the ground and supports a compass or other instrument.

Read more about Jacob's Staff:  Astronomy and Navigation, Surveying

Famous quotes containing the words jacob and/or staff:

    As for me, Abraham, Isaac, and Jacob are now only the subtlest imaginable essences, which would not stain the morning sky.
    Henry David Thoreau (1817–1862)

    I shall not want false witness to condemn me,
    Nor store of treasons to augment my guilt.
    The ancient proverb will be well effected:
    “A staff is quickly found to beat a dog.”
    William Shakespeare (1564–1616)